AJS & Matchless Owners Club

Hi all it's me again (sorry) , on stripping the head down I have noticed that the carb spacer to the head is home made out of a block of aluminium.
Please could someone send me the thickness of an original spacer so I can make sure it's correct.
Many thanks mat.

3/4"

Many thanks rob.

5/16"

3/4" on my 58 G2, 63 14 CSR & 66 G2 CSR, maybe 59 is different or all mine are wrong. All were on the bikes when I brought them. Heavyweights I have also 3/4" thick, bore dia. differs to suit carb bore.. You should soon find out, if 3/4" is too thick you won't get the nut on. You could do a rough check, put the carb on, do nuts up to show perhaps 2/3 turns protruding, measure approx. gap for spacer.

The black ?Bakelite? spacer I took off my carb measures slightly less than ¾" It is a 1964 CSR so has a different carb from the '59 G2 and therefore the thickness of the spacer could be different. The bore certainly is.

School day please. I thought our carbs had spacers made of an insulating material to reduce heat transference from the engine. If this is true, apart from not burning your fingers if you touch the carb, what benefit does it have and is a metal spacer as fitted to Mat's bike detrimental? My concern would be hot carb, vapourising fuel, boom.

I thought same as Janet, the spacer to stop heat. If its only to extend the port 3/4" they could have made it so in the head casting. All these spacers do seem to be 3/4" thick. That is the size given in parts lists for heavyweights. I measured mine fitted to lightweights. Not easy with a vernier. There's also paper gaskets in the gap between carb and head. As its just an insulator thickness would not be critical, seeing about 3/4" must be correct. They do come in various bore sizes, so it is important to get the correct bore size. I am sure if I had 5/16" spacer on any of my bikes, the stud would hit the carb body before I would get the nuts tight. You do need to pull the carb off the studs quite a bit, before you can get the nuts off the thread and out the gap between end of stud and carb flange. This distance only being a little more than the thickness of the nut. I do believe lights used 376 & 389 carbs so check which is correct for your year and model. I made a file of all carbs used on AMC with some brief details, I believe it is in tech tips. http://www.jampot.com/article_read.asp?id=551 Yes there's one. Must have done a file for AJS & Matchless. They are PDF files, my original file's are excel. I'll send anyone the excel version on request. so you can fill in all the gaps like bore size slide type etc if you wish. Details of which can be found in the archives. The Amal files will list all marques. So you can discover which marque your wrong carb was intended for. That takes time. You could sort my excel file to quickly discover if your wrong carb is correct for another AMC model/year. I also made excel files for Mag's & Dynamo's which I believe are also in tech tips. My file showing all old & new pt. no's of parts stocked by club spares made circa 2013 never did get published. It was not my file other companies used. I only gave that to the club, password protected. Like many other files, dating etc. If in the future these files are found, but cannot be opened, if no one can be found that I have given the password. Ask my son. I have left a file on my computer for him to find. He will be able to answer the question I have left, the answer being the password.